Tube Type Heat Exchanger and Manufacturing Method of the Same

ABSTRACT

Provided are a tube type heat exchanger and a method of the tube type heat exchanger capable of preventing spiral fins  12  from being deformed. In the tube type heat exchanger and the manufacturing method of the same according to the present invention, the plural spiral fins  12  are disposed in series in the axial direction so as to have edges of the spiral fins  12, 12  spaced apart from each other, and each holder  3  is disposed between the spiral fins  12, 12  and abuts to the outer circumference of the tube body  11.

TECHNICAL FIELD

The present invention relates to a tube type heat exchanger having plural heat transfer tubes disposed in series, and also relates to a manufacturing method of the tube type heat exchanger.

BACKGROUND ART

As a common tube type heat exchanger having plural heat exchange tubes disposed in series, there has been known a tube type heat exchanger including plural heat transfer tubes each of which has a tube body for flowing fluid therein and spiral fins disposed around an outer circumference of the tube body. Such a tube type heat exchanger is equipped with holders for holding the respective heat transfer tubes (Patent Document 1, for example).

PRIOR ART DOCUMENT Patent Document

-   Patent Document 1: Japanese Patent Laid-Open No. 2002-147988

SUMMARY OF INVENTION Problems to be Solved by the Invention

However, in the above mentioned tube type heat exchanger, the holders are configured to abut outer peripheries of the spiral fins so as to hold each heat transfer tube; consequently, the spiral fins may be deformed when weights of the heat transfer tubes are applied onto the spiral fins, for example. This may cause various problems such as deformation of the heat transfer tubes, which results in breakage or cracks on the heat transfer tubes, or causing variation in fluid flow of heating medium flowing outside the heat transfer tubes, which may deteriorate the heat exchange efficiency.

The present invention has been made in the light of the above problems, and an object is to provide a tube type heat exchanger and a manufacturing method of the same capable of preventing deformation of the spiral fins.

Solution to Problem

According to the present invention, there is provided a tube type heat exchanger, which includes plural heat transfer tubes disposed in series so as to set axial directions thereof to be parallel to each other, and holders for holding the heat transfer tubes, each of the heat transfer tubes including a tube body for flowing fluid therein, and spiral fins formed by disposing fins spirally around an outer circumference of the tube body, in each of the heat transfer tubes, the spiral fins being disposed in series in the axial direction so as to have edges of the spiral fins spaced apart from each other, and each of the holders being disposed between the spiral fins, and abutting the outer circumference of the tube body.

According to the tube type heat exchanger of the present invention, in each heat transfer tube, the spiral fins are disposed in series in the axial direction of the heat transfer tube to have edges of the spiral fins spaced apart from each other. Each holder disposed between the spiral fins abuts to the outer circumference of the tube body, so as to hold the heat transfer tube. Accordingly, each holder can hold each heat transfer tube without coming in contact with the spiral fins.

The tube type heat exchanger according to the present invention may have a configuration in which the spiral fins of each of the heat transfer tubes extend between spiral fins of another of the heat transfer tubes adjacently disposed in a radial direction of the heat transfer tube.

According to the tube type heat exchanger in such a configuration, the spiral fins of each of the heat transfer tubes extend between the spiral fins of another of the heat transfer tubes adjacently disposed in the radial direction of the heat transfer tubes. Accordingly, the spiral fins of the heat transfer tubes adjacently disposed overlap each other in the axial direction of the heat transfer tubes. Thus, it is possible to reduce the size of the device compared to a conventional tube type heat exchanger in which each holder comes in contact with outer circumferences of the spiral fins so as to hold the heat transfer tubes.

The tube type heat exchanger according to the present invention may have a configuration in which each of the holders includes a plurality of holding members for holding the tube bodies between the holding members.

According to the tube type heat exchanger in such a configuration, each of the holders holds the tube bodies with the plural holding members thereof. Accordingly, the holders can hold the respective tube bodies in a stable manner.

The tube type heat exchanger according to the present invention may have a configuration in which each of the holding members includes a plurality of holding portions for holding the tube bodies between the holding portions, and each of the holding portions has a recess so as to fit a part of each of the tube bodies in the recess.

According to the tube type heat exchanger in such a configuration, each of the plural holding portions has a recess so as to fit a part of each tube body in this recess and holds each tube body between the holding portions. Therefore, each tube body can be prevented from displacing relative to each holding member.

The tube type heat exchanger according to the present invention may have a configuration in which each of the holders further includes connecting members for connecting the holding members for holding the tube body between the holding members.

According to the tube type heat exchanger in such a configuration, each connecting member connects the holding members that hold the respective tube bodies between these holding members. Accordingly, since the holding members support each other, that is, reinforce each other through the connecting member, each holding member can be prevented from being bent or curved due to its own weight or load of the heat transfer tube.

According to the present invention, there is provided a method of manufacturing a tube type heat exchanger including plural heat transfer tubes disposed in series so as to set axial directions thereof to be parallel to each other, and holders for holding the heat transfer tubes, each of the heat transfer tubes including a tube body for flowing fluid therein, and spiral fins formed by disposing fins spirally around an outer circumference of the tube body, the method including: a step of cutting fins of each heat transfer tube so as to form a plurality of the spiral fins in series in the axial direction to have edges of the plurality of the spiral fins space apart from each other; and a step of disposing each of the holders between the spiral fins and bringing the holder in contact with the outer circumference of each of the tube bodies so as to hold the heat transfer tubes.

According to the manufacturing method of the tube type heat exchanger in such a configuration, it is possible to manufacture the tube type heat exchanger in such a manner that the fins of each heat transfer tube is cut so as to form the plural spiral fins disposed in series in the axial direction of each heat transfer tube to have edges of the spiral fins spaced apart from each other, and, in addition, each of the holders is disposed between the spiral fins so as to come in contact with the outer circumference of the tube bodies, thereby holding the respective heat transfer tubes without coming in contact with the spiral fins.

The manufacturing method of the tube type heat exchanger of the present invention may have a configuration in which the step of cutting the fins of each of the heat transfer tubes includes: rotating each of the heat transfer tubes around an axial center of the heat transfer tube by using a support member for supporting the heat transfer tube; and moving at least one of a cutting portion for cutting the fins and the support member in the axial direction of the heat transfer tube so as to provide relative displacement in axial direction between the cutting portion and the heat transfer tube.

According to the manufacturing method of the tube type heat exchanger in such a configuration, the support member for supporting the heat transfer tube rotates the heat transfer tube around the axial center of the heat transfer tube. In addition, at least one of the cutting portion for cutting the fins and the support member moves in the axial direction of the heat transfer tube, thereby providing relative displacement between the cutting portion and the heat transfer tube in the axial direction of the heat transfer tube. Accordingly, the cutting portion can cut the spiral fins accurately.

Effects of Invention

As described above, according to the tube type heat exchanger and the manufacturing method of the tube type heat exchanger, each holder can hold the respective heat transfer tubes without coming in contact with the spiral fins; accordingly it is possible to prevent the spiral fins from being deformed.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a general drawing illustrated in a perspective view of the tube type heat exchanger according to one embodiment of the present invention.

FIG. 2 is a schematic drawing illustrated in an internal plan view of main portions of the tube type heat exchanger according to the embodiment.

FIG. 3 is a schematic drawing illustrated in a perspective view of main portions of the heat transfer tubes and the holders in the tube type heat exchanger according to the embodiment.

FIG. 4 is a schematic drawing illustrated in a perspective view of main portions of the holders in the tube type heat exchanger according to the embodiment.

FIG. 5 are general drawings of the holding members of the holder according to the embodiment, in which FIGS. 5( a) and 5(b) illustrate front views thereof, respectively.

FIG. 6 are general drawings of the connecting member in the holder according to the embodiment, in which FIG. 6( a) is a plan view thereof, FIG. 6( b) is a front view thereof, and FIG. 6( c) is a side view thereof, respectively.

FIG. 7 are drawings of explaining the manufacturing method of the heat transfer tube in the tube type heat exchanger according to the embodiment, in which FIG. 7( a) is a longitudinal sectional view thereof, and FIG. 7( b) is a cross sectional view taken along line A-A of FIG. 7( a).

FIG. 8 are drawings of explaining the manufacturing method of the heat transfer tube in the tube type heat exchanger according to the embodiment, in which FIG. 8( a) is a longitudinal sectional view thereof, and FIG. 8( b) is an enlarged cross sectional view taken along line B-B of FIG. 8( a).

FIG. 9 are schematic drawings of main portions of the tube type heat exchanger according to another embodiment of the present invention, in which FIG. 9( a) is a perspective view of the holder, and FIG. 9( b) is a perspective view of the heat transfer tubes and the holder.

FIG. 10 are drawings of explaining the manufacturing method of the heat transfer tube in the tube type heat exchanger according to further another embodiment of the present invention, in which FIG. 10( a) and FIG. 10( b) are the longitudinal sectional views thereof, respectively.

DESCRIPTION OF EMBODIMENTS

Hereinafter, descriptions will be provided on one embodiment of the tube type heat exchanger according to the present invention, with reference to FIGS. 1 to 8.

As illustrated in FIGS. 1 to 6, the tube type heat exchanger according to the present embodiment includes plural heat transfer tubes 1 disposed in series such that the axial direction of each heat transfer tube becomes parallel (substantially parallel) to each other, a main body 2 for housing the heat transfer tubes 1 therein, and plural holders 3 for holding the respective heat transfer tubes 1. Concerning the tube type heat exchanger according to the present embodiment, the heat transfer tube 1 is referred to as a “tube”, the main body 2 is referred to as a “shell” and the heat exchanger is referred to as a “shell and tube type heat exchanger”, commonly.

Each heat transfer tube 1 includes a tube body 11 for flowing fluid such as gas and liquid (heat transfer target object) through inside the tube body 11, and spiral fins 12 disposed around the outer circumference of the tube body 11. Each heat transfer tube 1 is fixed to the main body 2 by coupling both ends of the tube body 11 to the main body 2.

The respective plural heat transfer tubes 1 are disposed in plural rows in the radial direction (in the vertical and or horizontal directions) of the heat transfer tubes 1 in such a manner that each heat transfer tube 1 has an equal distance from its own axial center to the axial center of another heat transfer tube 1 adjacently disposed in the radial direction of the heat transfer tube 1. At this time, the outer periphery portions (outer edge) of the spiral fins 12 of each heat transfer tube 1 extend into between the spiral fins 12 of another heat transfer tube 1 adjacently disposed in the radial direction of the heat transfer tube 1 of interest. Specifically, the both spiral fins 12, 12 of the heat transfer tubes 1 disposed adjacently in the radial direction of the heat transfer tubes 1 overlap each other in the axial direction of the heat transfer tubes 1.

Each tube body 11 has an equal diameter in the axial direction, and is formed in a straight tube. Each tube body 11 is formed of metal material having high thermal conductivity such as carbon steel and stainless steel.

The spiral fins 12 of each heat transfer tube 1 are provided such that plural spiral fins are disposed in series in the axial direction of the heat transfer tube 1 to have adjacent edges of the spiral fins spaced apart from each other in the axial direction. Each spiral fin 12 is provided by forming fins 121 spirally around the outer circumference of the tube body 11 (a single spiral on the outer circumference of the tube body 11 is referred to as one “fin” in the present application). The spiral fin 12 is formed of metal material having high thermal conductivity such as aluminum and copper.

The spiral fin 12 is composed of a plate body extending in the radial direction from the heat transfer tube 1 (tube body 11), and is formed in spiral plate body whose axial center coincides with the axial center of the heat transfer tube 1 (tube body 11). Each spiral fin 12 includes the fins 121 disposed in series with an equal interval between the fins 121 in the axial direction of the heat transfer tube 1.

The spiral fins 12 of each heat transfer tube 1 includes the fins 121 whose spiral direction is reversed to the fins 121 included in the spiral fins 12 of another heat transfer tube 1 adjacently disposed. In such a configuration, the spiral fins 12, 12 of the heat transfer tubes 1 adjacently disposed to each other in the radial direction of the heat transfer tubes 1 are disposed so as to have their fins 121 parallel to each other.

The main body 2 includes a cylindrical body 21 having a sealed space therein, a fluid inlet 22 for introducing the fluid into the cylindrical body 21, a first reserving chamber 23 for branching the fluid flown from the fluid inlet 22 to the respective heat transfer tubes 1 on a first half side, a second reserving chamber 24 for collecting the fluid flown from the respective heat transfer tubes 1 on the first half side and branching the collected fluid to the respective heat transfer tubes 1 on a second half side, a third reserving chamber 25 for collecting the fluid flow from the respective heat transfer tubes 1 on the second half side, and a fluid outlet 26 for discharging the fluid in the third reserving chamber 25 out of the cylindrical body 21.

The main body 2 further includes a medium inlet 27 for introducing the thermal medium (heating medium or cooling medium) such as gas and fluid into the cylindrical body 21, and a medium outlet 28 for discharging the thermal medium having flown inside the cylindrical body 21 and outside the respective heat transfer tubes 1 out of the cylindrical body 21. In FIG. 1 and FIG. 2, the flow of the fluid is represented by the arrows of solid lines and the flow of the thermal medium is represented by the arrows of broken lines.

In the main body 2, one end of each heat transfer tube 1 on the first half side is connected to a side wall of the first reserving chamber 23 and the other end of each heat transfer tube 1 on the first half side is connected to a side wall of the second reserving chamber 24, thereby fixing the both ends of each heat transfer tube 1 on the first half side. In addition, in the main body 2, one end of each heat transfer tube 1 on the second half side is connected to a side wall of the third reserving chamber 25 and the other end of each heat transfer tube 1 on the second half side is connected to the side wall of the second reserving chamber 24, thereby fixing the both ends of each heat transfer tube 1 on the second half side.

Each holder 3 includes plural holding members 31 each of which is disposed between the spiral fins 12, 12 and holding the respective tube bodies 11 between the holding members 31, and plural connecting members 32 each of which connects the holding members 31, 31 disposed between the spiral fins 12, 12 and holding the respective tube bodies 11 therebetween. Each holder 3 also includes a fixing member 33 for fixing the corresponding holding member 31 to the main body 2.

In the above configuration, each holder 3 is disposed between the spiral fins 12, 12 and abuts to the outer circumference of the tube body 11 so as to hold each heat transfer tube 1 without coming in contact with the spiral fins 12. The plural holders 3 are disposed in series in the axial direction of each heat transfer tube 1 and the holders 3 hold each heat transfer tube 1 at plural portions of the heat transfer tube 1.

Each holding member 31 is formed into a long plate shape, and has plural holding portions 311 on the upper and lower edges of the holding member 31 so as to hold the respective tube bodies 11. Each holding member 31 includes locking portions 312 for locking the connecting members 32 so as to prevent relative displacement of the connecting members 32. Each holding member 31 is provided with holes 313, 313 at the both longitudinal ends thereof so as to be fixed to the cylindrical body 21 of the main body 2 by using the fixing members 33.

The longitudinal direction of the holding members 31 is disposed orthogonally to the axial direction of the respective heat transfer tubes 1 (tube bodies 11), and is disposed parallel to each other in the vertical direction thereof. There are two types (FIG. 5( a) and FIG. 5( b)) in the holding members 31, which have different layouts of the holding portions 311 and the locking portions 312, so that the holding portions 311 the locking portions 312 are alternatingly disposed with each other in the vertical direction.

Each of the holding portions 311 is formed in a semicircular recess at the upper edge of each holding member 31 so that the lower half of each tube body 11 is fit in this upper recess, and also in a semicircular recess at the lower edge of each holding member 31 so that the upper half of each tube body 11 is fit in this lower recess. Each locking portion 312 is formed in a rectangular recess at the upper edge of each holding member 31 so that each connecting member 32 is fit in this rectangular recess to be locked thereby.

Each connecting member 32 includes a first fitting portion 321 in a recess shape for fitting therein the lower edge of the holding member 31, and a second fitting portion 322 in a recess shape for fitting therein the upper edge of another holding member 31 disposed immediately below the holding member 31 of interest. The connecting member 32 also includes a to-be-locked portion 323 disposed between the fitting portions 321 and 322 and is locked on the locking portion 312 of the holding member 31.

The configuration of the tube type heat exchanger according to the present embodiment has been described above, and descriptions will now be provided on a manufacturing method of the tube type heat exchanger according to the present embodiment.

As illustrated in FIG. 7, in the first step (step of forming the spiral fins), the spiral fins 12 of the heat transfer tube 1 are formed by a form rolling device 7. Prior to the description of the first step, the form rolling device 7 and material of the heat transfer tube 1 will now be described.

The form rolling device 7 includes plural form rolling portions 71 each of which has a spiral disk blade 711 and a support member (not illustrated) 72 for supporting the heat transfer tube 1. Each disk blade 711 of the form rolling portions 71 rotates around the axial center of the heat transfer tube 1 and pushes the heat transfer tube 1 from the outside in the radial direction of the heat transfer tube 1.

The support member 72 rotates the heat transfer tube 1 around the axial center of the heat transfer tube 1, and also moves itself in the axial direction of the heat transfer tube 1 while supporting the heat transfer tube 1. The heat transfer tube 1 is manufactured by raw material including an inner tube 1 a made of carbon steel, stainless steel or the like and an outer tube 1 b made of aluminum, copper or the like, which is coated on the inner tube 1 a.

In the first step, the respective form rolling portions 71 press the outer tube 1 b from three directions while rotating, and the support member 72 moves the heat transfer tube 1 in the axial direction of the heat transfer tube 1 while rotating this heat transfer tube 1. By this, the inner tube 1 a is compressively crimped to the outer tube 1 b, at the same time the outer tube 1 b is extruded (expanded) in the radial direction of the heat transfer tube 1. Then, the disk blades 711 in a spiral shape cut the outer tube 1 b extruded in the radial direction of the heat transfer tube 1 into the spiral fin 12 in a spiral form.

As illustrated in FIG. 8, in the second step (step of cutting fins), the cutting device 8 cuts the fins 121 (part of the spiral fin 12) of the heat transfer tube 1. Prior to the descriptions of the second step, the cutting device 8 will be described as follow.

The cutting device 8 includes a cutting portion 81 having plural disk blades 811 and a support member (not illustrated) 82 for supporting the heat transfer tube 1. The disk blades 811 of the cutting portion 81 come in or out of contact with the heat transfer tube 1 in the radial direction of the heat transfer tube 1 while rotating around the axial center of the heat transfer tube 1, and the support member 82 rotates the heat transfer tube 1 around the axial center of the heat transfer tube 1, and moves itself along the axial direction of the heat transfer tube 1 while supporting the heat transfer tube 1.

In the second step, the disk blades 811 of the cutting portion 81 rotate and come close to the heat transfer tube 1 so as to cut the heat transfer tube 1 to a predetermined inner periphery (base end) of predetermined fins 121 by the disk blades 811. Following this operation, the support member 82 rotatingly moves the heat transfer tube 1 in the axial direction of the heat transfer tube 1, so as to cut the fins 121 by the disk blades 811 with the center of the thickness direction of the disk blades 811 kept coincide with the center of the thickness direction of the fins 121.

In such a manner, the single spiral fin 12 of the heat transfer tube 1 is divided into a plurality of the spiral fins 12, 12. Accordingly, the heat transfer tube 1 has the plural spiral fins 12, 12 disposed in series in the axial direction of the heat transfer tube 1 to have the edges of the adjacent spiral fins 12, 12 spaced apart from each other.

In the third step (step of assembling), the respective heat transfer tubes 1 and the respective holders 3 are assembled. Specifically, as illustrated in FIG. 2 and FIG. 3, each holder 3 is disposed between the spiral fins 12, 12 that are spaced from each other. The respective holding members 31 and the respective connecting members 32 are assembled such that each holder 3 comes in contact with the outer circumferences of the respective tube bodies 11 so as to hold the heat transfer tube 1.

As described above, according to the tube type heat exchanger of the present embodiment, the plural spiral fins 12, 12 are disposed in series in the axial direction of each heat transfer tube 1 such that the spiral fins 12, 12 adjacently disposed in the axial direction of the heat transfer tube 1 are spaced from each other. Each holder 3 is disposed between the spiral fins 12, 12 so as to abut the outer circumference of the tube body 11, thereby holding the respective heat transfer tube 1. Accordingly, each of the holders 3 can hold the respective heat transfer tubes 1 without coming in contact with the spiral fins 12, thereby preventing the spiral fins 12 from being deformed.

According to the tube type heat exchanger of the present embodiment, the respective heat transfer tubes 1 are disposed in such a manner that the spiral fins 12 of each heat transfer tube 1 extend between the spiral fins 12 of another heat transfer tube 1 adjacently disposed in the radial direction of the heat transfer tube 1. The heat transfer tubes 1 disposed adjacently to each other in the radial direction of the heat transfer tubes 1 overlap each other in the both spiral fins 12, 12 in the axial direction of these heat transfer tubes 1. Thus, the reduction in size of the device can be achieved.

According to the tube type heat exchanger of the present embodiment, the plural holding members 31 hold the respective tube bodies 11 therebetween so that each holder 3 can hold the respective tube bodies 11 in a stable manner. In addition, the holding portions 311, each of which is formed in a recess, each fit a part of each of the respective tube bodies 11 in each of these recesses and hold the respective tube bodies 11 therebetween. Thus, it is possible to prevent these respective tube bodies 11 from displacing relative to the respective holding members 31.

According to the tube type heat exchanger of the present embodiment, each connecting member 32 connects the two holding members 31, 31 for holding the tube body 11 therebetween. In such a configuration, since both the holding members 31, 31 support each other, that is, reinforce each other through the connecting member 32, each holding member 31 can be prevented from being bent or curved due to its own weight or load of the heat transfer tube 1.

The tube type heat exchanger and the manufacturing method thereof according to the present invention is not limited to the above described embodiment, and it is needless to mention that various modifications can be made without departing from the scope of the invention. It is also needless to mention that any of the configurations and the methods concerning the following modifications may be chosen to be applied to the configurations and the methods according to the above described embodiment.

For example, in the tube type heat exchanger of the above described embodiment, the example has been described in which the spiral fins 12, 12 adjacently disposed in radial direction of the heat transfer tubes 1 overlap each other in the axial direction of the heat transfer tubes 1; but the present invention is not limited to this, and the heat transfer tubes 1 may be disposed such that the spiral fins 12, 12 adjacently disposed in the radial direction of the heat transfer tubes 1 do not overlap each other in the axial direction of the heat transfer tubes 1, that is, these spiral fins 12, 12 may be disposed apart from each other.

In the tube type heat exchanger of the above described embodiment, the example has been described in which the heat transfer tubes 1 are disposed such that the axial direction of the heat transfer tubes 1 are set to be horizontally (laterally); but the present invention is not limited to this, and for example, the axial direction of the heat transfer tubes 1 may be disposed perpendicularly (vertically), or the axial direction of the heat transfer tubes 1 may be inclined relative to the horizontal direction.

In the tube type heat exchanger of the above described embodiment, the example has been described in which the holding members 31, 31 hold the respective tube bodies 11 therebetween in the vertical direction, so as to support the respective tube bodies 11; but the present invention is not limited to this, and for example, as illustrated in FIG. 9, the holder 30 may include the plural support members 301 for supporting the lower portions of the respective tube bodies 11, and each support member 301 is provided with the recesses 302 on the upper edge of the support member 301, so as to fit the lower portions of the tube bodies 11 in these recesses 302 for the purpose of preventing the tube bodies 11 from relatively displacing, thereby supporting the tube bodies 11.

In the tube type heat exchanger of the above described embodiment, the example has been described in which each connecting member 32 fits the holding members 31, 31 in the fitting portions 321, 322 thereof, thereby connecting the holding members 31, 31 to each other; but the present invention is not limited to this. For example, the holding members may be coupled to each other by using coupling means as the connecting member.

In the tube type heat exchanger of the above described embodiment, the example has been described in which the spiral fins 12, 12 of each heat transfer tube 1 are formed to be spaced from each other by cutting the fins 121 (part of the spiral fin 12); but the present invention is not limited to this.

For example, each heat transfer tube may be formed by using the tube body and the spiral fin that are separate members, respectively. Specifically, ultra high frequency current may be applied to the spiral fins and the tube body so as to continuously weld the spiral fins disposed on the outer circumference of the tube body, thereby forming plural spiral fins in series in the axial direction of the heat transfer tube such that the spiral fins adjacently disposed in the axial direction of the heat transfer tube are spaced from each other; or the tube body may be expanded outward so as to securely attach to the spiral fins disposed on the outer circumference, thereby forming plural spiral fins in series in the axial direction of the tube body such that the spiral fins adjacently disposed in the axial direction of the heat transfer tube are spaced from each other.

As illustrated in FIG. 10, each heat transfer tube 10 may be configured such that the outer tube 10 b is covered on the inner tube 10 a, and the outer tube 10 b includes smaller diameter portions 10 c. In such a configuration, the form rolling device 7 forms the spiral fins 12 on a greater diameter portion 10 d but forms no spiral fin 12 on the smaller diameter portion 10 c. In this way, plural spiral fins 12 are formed in series in the axial direction of the heat transfer tube 1 such that the spiral fins 12, 12 adjacently disposed in the axial direction of the heat transfer tube 1 are spaced from each other.

In the tube type heat exchanger of the above described embodiment, the example has been described in which the support member 82 of the cutting device 8 moves in the axial direction of the heat transfer tube 1, such that the cutting portion 81 displaces relative to the heat transfer tube 1 in the axial direction of the heat transfer tube 1; but the present invention is not limited to this, and for example, the cutting portion 81 may move, or the cutting portion 81 along with the support member 82 may move in the axial direction of the heat transfer tube 1, such that the cutting portion 81 displaces relative to the heat transfer tube 1 in the axial direction of the heat transfer tube 1.

In the tube type heat exchanger of the above described embodiment, the example has been described in which the support member 72 of the form rolling device 7 and the support member 82 of the cutting device 8 are provided as separate members, respectively; but the present invention is not limited to this, and the support member 72 of the form rolling device 7 and the support member 82 of the cutting device 8 may be a common support member.

REFERENCE SIGNS LIST

-   -   1 Heat transfer tube     -   2 Main body     -   3 Holder     -   7 Form rolling device     -   8 Cutting device     -   10 Heat transfer tube     -   11 Tube body     -   12 Spiral fin     -   30 Holder     -   31 Holding member     -   32 Connecting member     -   121 Fin     -   311 Holding portion 

1. A tube type heat exchanger comprising plural heat transfer tubes disposed in series so as to set axial directions thereof to be parallel to each other, and holders for holding the heat transfer tubes, each of the heat transfer tubes including a tube body for flowing fluid therein, and spiral fins formed by disposing fins spirally around an outer circumference of the tube body, in each of the heat transfer tubes, the spiral fins being disposed in series in the axial direction so as to have edges of the spiral fins spaced apart from each other, and each of the holders being disposed between the spiral fins, and abutting the outer circumference of the tube body.
 2. The tube type heat exchanger according to claim 1, wherein the spiral fins of each of the heat transfer tubes extend between spiral fins of another of the heat transfer tubes adjacently disposed in a radial direction of the heat transfer tube.
 3. The tube type heat exchanger according to claim 1 or claim 2, wherein each of the holders includes a plurality of holding members for holding the tube bodies between the holding members.
 4. The tube type heat exchanger according to claim 3, wherein each of the holding members includes a plurality of holding portions for holding the tube bodies between the holding portions, and each of the holding portions has a recess so as to fit a part of each of the tube bodies in the recess.
 5. The tube type heat exchanger according to claim 3, wherein each of the holders further includes connecting members for connecting the holding members for holding the tube body between the holding members.
 6. A method of manufacturing a tube type heat exchanger including plural heat transfer tubes disposed in series so as to set axial directions thereof to be parallel to each other, and holders for holding the heat transfer tubes, each of the heat transfer tubes including a tube body for flowing fluid therein, and spiral fins formed by disposing fins spirally around an outer circumference of the tube body, the method comprising: a step of cutting fins of each heat transfer tube so as to form a plurality of the spiral fins in series in the axial direction to have edges of the spiral fins spaced apart from each other; and a step of disposing each of the holders between the spiral fins and bringing the holder in contact with the outer circumference of each of the tube bodies so as to hold the heat transfer tubes.
 7. The method of manufacturing a tube type heat exchanger according to claim 6, wherein the step of cutting the fins of each of the heat transfer tubes includes: rotating each of the heat transfer tubes around an axial center of the heat transfer tube by using a support member for supporting the heat transfer tube; and moving at least one of a cutting portion for cutting the fins and the support member in the axial direction of the heat transfer tube so as to provide relative displacement in axial direction between the cutting portion and the heat transfer tube. 